Trialing system and method for modular hip joint replacement system

Abstract

A system and method for trialing a modular hip replacement system ( 10 ) permits evaluation and replication of the anatomic anteversion rotational angle of the femur. A distal stem component ( 18 ) of the hip replacement system ( 10 ) includes a proximal portion ( 34 ) having a locator feature ( 35 ) that is externally accessible when the stem component is mounted within the femur. A proximal trial body assembly ( 60 ) is mounted on the proximal portion ( 34 ) of the distal stem component ( 18 ) to permit rotation of a trial neck component ( 62 ). The trial neck component ( 62 ) also includes a locator feature ( 126 ) that can be externally referenced to determine the anteversion angle.

1. A trialing system for use with a modular hip replacement system, comprising:
 a stem component configured to be fixed within a prepared bone, the stem component including a proximal portion defining a longitudinal axis and defining a stem locator feature indicative of an orientation of the stem component with respect to the longitudinal axis; 
 a keyed trial component configured to engage the proximal portion in a keyed relationship while allowing access to the stem locator feature; and 
 a trial neck component including a trial locator feature and engageable with the proximal portion and matable with the keyed trial component at a plurality of angles in a plane perpendicular to the longitudinal axis, such that when the keyed trial component is keyedly engaged with the proximal portion, the trial neck component can be i) engaged with the proximal portion, ii) rotated to a selected one of the plurality of angles with respect to the keyed trial component, and iii) mated to the keyed trial component, while allowing access to the stem locator feature and to the trial locator feature; 
 wherein the keyed trial component includes a discrete first plurality of splines at a proximal end thereof, said discrete first plurality of splines configured to extend perpendicularly to the longitudinal axis when the keyed trial component is engaged with the proximal portion; and the trial neck component includes a second plurality of splines, the second plurality of splines formed complementary to the first plurality of splines; and 
 wherein the keyed trial component comprises a first bore with a first diameter, the first bore extending from a distal end of the keyed trial component to a proximal end of the keyed trial component; the proximal portion comprises an elongated portion extending proximally from a widened portion, the elongated portion sized to extend through the first bore, and the widened portion including a dimension wider than the first diameter; and the stem locator feature is located on the elongated portion such that when the keyed trial component is engaged with the proximal portion, the stem locator feature is located proximal to the proximal end of the keyed trial component alone the longitudinal axis. 
 
     
     
       2. The trialing system of  claim 1 , wherein the trial neck component comprises:
 a second bore with a second diameter, the second bore extending from a distal end of the trial neck component to a proximal end of the trial neck component, the second bore sized to receive the elongated portion such that when the keyed trial component is engaged with the proximal portion and the trial neck component is engaged with the proximal portion, the stem locator feature is accessible through the second bore. 
 
     
     
       3. The trialing system of  claim 2 , wherein:
 the proximal end of the keyed trial component defines a first plurality of splines configured to extend perpendicularly to the longitudinal axis when the keyed trial component is engaged with the proximal portion; and 
 the distal end of the trial neck component defines a second plurality of splines, the second plurality of splines formed complementary to the first plurality of splines. 
 
     
     
       4. The trialing system of  claim 1 , wherein:
 the stem component comprises a distal portion curved in a plane of curvature; and 
 the stem locator feature is oriented at a predetermined angle relative to the plane of curvature. 
 
     
     
       5. The trialing system of  claim 4 , wherein the stem locator feature is a recess. 
     
     
       6. The trialing system of  claim 5 , wherein the stem locator feature defines an ovoid in a plane perpendicular to the longitudinal axis. 
     
     
       7. A trialing system for use with a modular hip replacement system, comprising:
 a stem component configured to be fixed within a prepared bone, the stem component including a proximal portion with a ledge and an elongated portion extending proximally from the ledge, the elongated portion defining a longitudinal axis and defining a stem locator feature; 
 a keyed trial component configured to be positioned upon the ledge in a keyed relationship with the proximal portion; and 
 a trial neck component including a trial locator feature and engageable with the elongated portion and matable with the keyed trial component at a plurality of angles in a plane perpendicular to the longitudinal axis, such that when the keyed trial component is keyedly engaged with the elongated portion, the trial neck component can be i) engaged with the elongated portion, ii) rotated to a selected one of the plurality of angles with respect to the keyed trial component, and iii) mated to the keyed trial component, while allowing access to the stem locator feature and to the trial locator feature; 
 wherein the keyed trial component comprises a first bore with ledge; the bore ledge is configured to be positioned on the stem ledge; the first bore extends proximally from the bore ledge to a proximal end of the keyed trial component; and the height of the first bore from the bore ledge to the proximal end of the keyed trial component is less than the length of the elongated portion alone the longitudinal axis, such that when the keyed trial component is positioned on the ledge, the stem locator feature is located proximal to the proximal end of the keyed trial component along the longitudinal axis; and 
 wherein the proximal end of the keyed trial component defines a discrete first plurality of splines configured to extend perpendicularly to the longitudinal axis when the keyed trial component is engaged with the proximal portion; and a distal end of the trial neck component defines a second plurality of splines, the second plurality of splines formed complementary to the first plurality of splines. 
 
     
     
       8. The trialing system of  claim 7 , wherein the trial neck component comprises:
 a second bore extending from a distal end of the trial neck component to a proximal end of the trial neck component, the second bore sized to receive the elongated portion such that when the keyed trial component is positioned on the ledge, the stem locator feature is accessible through the second bore. 
 
     
     
       9. The trialing system of  claim 7 , wherein:
 the stem component comprises a distal portion curved in a plane of curvature; and 
 the stem locator feature is oriented at a predetermined angle relative to the plane of curvature. 
 
     
     
       10. The trialing system of  claim 7 , wherein the stem locator feature defines an ovoid in a plane perpendicular to the longitudinal axis. 
     
     
       11. A trialing system for use with a modular hip replacement system, comprising:
 a stem component configured to be fixed within a prepared bone, the stem component including a proximal portion with an elongated portion and a keyed portion, the elongated portion defining a longitudinal axis and defining a stem locator feature; 
 a keyed trial component configured to be mated with the keyed portion in a keyed relationship with the proximal portion; and 
 a trial neck component including a trial locator feature and engageable with the elongated portion and matable with the keyed trial component at a plurality of angles in a plane perpendicular to the longitudinal axis, such that when the keyed trial component is keyedly engaged with the elongated portion, the trial neck component can be i) engaged with the elongated portion, ii) rotated to a selected one of the plurality of angles with respect to the keyed trial component, and iii) mated to the keyed trial component, while allowing access to the stem locator feature and to the trial locator feature; 
 wherein the elongated portion extends proximally from an enlarged portion; the keyed trial component comprises a first bore; the first bore extends from a distal end of the keyed trial component to a proximal end of the keyed trial component and includes an internal ledge; the diameter of the first bore distal to the internal ledge is greater than the diameter of the enlarged portion; and the diameter of the first bore proximal to the internal ledge is less than the diameter of the enlarged portion and greater than the diameter of the elongated; and 
 wherein the proximal end of the keyed trial component defines a discrete first plurality of splines configured to extend perpendicularly to the longitudinal axis when the keyed trial component is engaged with the proximal portion; and a distal end of the trial neck component defines a second plurality of splines, the second plurality of splines formed complementary to the first plurality of splines. 
 
     
     
       12. The trialing system of  claim 11 , wherein:
 the elongated portion defines a generally cylindrical periphery about the longitudinal axis; and 
 the keyed portion comprises a flat area of the generally cylindrical periphery. 
 
     
     
       13. The trialing system of  claim 11 , wherein the trial neck component comprises:
 a second bore extending from a distal end of the trial neck component to a proximal end of the trial neck component, the second bore sized to receive the elongated portion such that when the keyed trial component is mated with the keyed portion and the trial neck component is engaged with the proximal portion, the stem locator feature is accessible through the second bore. 
 
     
     
       14. The trialing system of  claim 13 , wherein:
 the stem component comprises a distal portion curved in a plane of curvature; and 
 the stem locator feature is oriented parallel to the plane of curvature. 
 
     
     
       15. The trialing system of  claim 14 , wherein the stem locator feature defines an ovoid in a plane perpendicular to the longitudinal axis.